The invention relates to filter cartridge dust collectors, and in particular to a horizontally mounted filter cartridge dust collector and support system therefor, which is internal to the housing of the collector and external to the cartridges. The support system permits the use of a single access door through which all of the cartridge rows may be accessed and an improved clamping mechanism for compressing and retaining the cartridges in place.
A variety of different air filter systems exist which use different types and orientations of filter elements, such as baghouses in which filter bags typically are vertically disposed (as shown, for example, in U.S. Pat. No. 4,435,197 to Nijhawan et al.) and dust collectors which use horizontally mounted filter tubes or bags (as shown, for example, in U.S. Pat. No. 4,343,632 to Margraf). Horizontally mounted, cylindrical pleated cartridges are another common type of filter element, such as disclosed in U.S. Pat. No. 4,050,504 to Howeth.
A number of different cartridge support and housing structures have been employed for horizontally mounted filter cartridges. Typically, the horizontally mounted filter cartridge systems utilize a separate access door for each cartridge or row of cartridges, as evidenced by the TORIT, FABRICMAX, DUST-HOG, and STERNPULSE dust collectors marketed, respectively, by the Donaldson Co., PTS Industries, United Air Specialists, and the Sternvent Co.
The TORIT System includes a number of horizontally mounted filter cartridges supported inside the housing using an internal truss-like structure or yoke, which extends from the tube sheet to the front plate of the housing. The front plate includes a number of holes for mounting the individual cartridges. In such an arrangement, the front plate and tube sheet provide support for the ends of the filter cartridges, while the internal truss structure supports the interior of the cartridges, which may be arranged in rows of multiple in-line cartridges supported by the truss.
This type of support system has a number of drawbacks and disadvantages--for instance, the separate access door for each cartridge or row of cartridges. With separate doors, servicing of the cartridges and inspection of the system is difficult because the single row access doors do not allow for visual inspection of other cartridge rows, nor of the interior of the dirty air plenum. Thus, in the event of a cartridge failure, each individual cartridge row may have to be removed to find the faulty cartridge. A further disadvantage of such system is the high manufacturing and labor costs necessitated because of the need to cut and machine multiple access holes, and fabricate and mount the individual doors.
Another problem that exists in such filter cartridge systems is that the use of the internal truss support structure can result in cartridge instability, which may cause improper sealing of the cartridges. A tight fit between the truss and the cartridge is difficult to achieve due to the required tolerance with the inner diameter of the cartridge. As a result, there often exists a certain amount of play or looseness between the truss structure and the cartridges. Consequently, the cartridges are unstable and may become misaligned, especially during compression of the cartridges, thereby resulting in defective sealing.
Clamping mechanisms and gaskets have been frequently used to provide the requisite compression and sealing of the cartridges. For example, the TORIT system utilizes a handle, an access cover and a gasket to compress and seal the cartridges. Rotation of the handle applies pressure from the access cover to the cartridge to compress the gaskets disposed between the cover and the outer cartridge, between the cartridges themselves, and between the inner cartridge and the tube sheet. The problem with this type of cartridge clamping mechanism is that by turning the handle torque may be applied to the access cover. This can result in undesired twisting of the access cover, cartridges (due to their loose support on the internal yoke), and/or the gaskets, which may produce misalignment or damage to the gaskets. Either of these two conditions greatly increase the risk of improper sealing and possible leakage of dirty air into the clean air chamber, which decreases performance of the system.
U.S. Pat. No. 4,650,504 to Howeth discloses a different type of clamping mechanisms that may be used in a filter system having horizontally mounted filter cartridges (FIG. 3) or vertically mounted filter cartridges (FIG. 5). In the horizontally mounted system, turning of a threaded bolt axially moves a gimbal plate along tension bars to compress an end seal. Again, this arrangement may produce the undesirable application of torque to gimbal plate, seal and cartridge. Similarly, the clamping mechanism for vertically mounted cartridges includes a bolt threaded through a clamping bar. Rotation of the bolt axially compresses a gimbal plate and a gasket via a cylindrical sleeve connected to gimbal plate. Undesirable torque may be transmitted to the gimbal plate, seal, and cartridge by the sleeve.
U.S. Pat. No. 4,871,380 to Meyers discloses a cartridge clamping mechanism (FIG. 5) which accomplishes the requisite compression sealing by means of a spring loaded clamping plate instead of the usual threaded rod. This type of clamping mechanism still requires the use of some rotational force, which may impart undesired torque, and introduces the use of an additional element--a compression spring--that is susceptible to wear.
Horizontally mounted filter cartridge systems having a single door providing access to a bank of filter cartridges are known from the patent literature, but have not been widely commercialized. U.K. Patent Application GB 2088744 discloses an air filter system that includes two banks of filter cartridges mounted horizontally on support structures disposed inside the housing. A single door provides access to each bank of cartridges. However, each row of the cartridge in a bank contains only a single cartridge. Because the depth of the system is only one cartridge per row, such a system has a limited capacity.
U.S. Pat. No. 4,871,380 to Meyers discussed above discloses a dust collector having cartridge rows of two in-line cartridges. These cartridges are mounted in a cage on three rods, which are external to the cartridges. However, Meyers does not provide a single access door, but instead suffers from disadvantages discussed above associated with the use of multiple access holes and doors.
More recently, horizontally mounted cartridge filter systems having a single door providing access to rows of multiple in-line cartridges have become available. Examples of such systems include the MRWH Series Cartridge Type Collectors, and the INTERCEPT Horizontal Cartridge Dust Collectors, available from Murphy-Rogers, Inc. and Polaris Industrial Ventilation, Inc., respectively. The MRWH Cartridge Type Collector includes horizontally mounted filter cartridges which may be mounted in rows having two cartridges each. The MRWH system is believed to include an internal structure for supporting the cartridges similar to the truss structure described in the TORIT system above. Thus, this system also suffers from the drawbacks of having loosely mounted cartridges, with the resultant cartridge instability, misalignment, and sealing problems.
The foregoing demonstrates a need for a horizontally mounted filter cartridge dust collector having a single access door and a cartridge support system that provides stable support for rows of multiple in-line cartridges. There is also a need for a clamping mechanism to compress and seal the cartridges in a filter cartridge dust collector of any type that prevents misalignment and improper sealing of the cartridges and gaskets.